The present invention relates generally to data processing system and, more particularly, to a new and novel disk array subsystem for use in a data processing system.
One well known problem associated with data processing systems is computer system throughput, namely, the relatively slow rate at which mass storage devices are capable of accessing data.
Generally speaking, CPU's are capable of processing data much more quickly than mass storage devices are capable of delivering data. Consequently, a CPU often loses time, standing idle, while waiting for needed data to be transferred thereto from a mass storage device. As can readily be appreciated, this inefficiency frequently results in a waste of the tremendous horsepower of the CPU, which does not achieve maximum performance.
In the past, approaches utilizing disk caches and data base segmenting were developed to minimize this problem. However, none of these approaches met all of the requirements of a high-transaction processing environment.
Recently, subsystems comprising disk arrays, i.e., groups of small, independent disk drive modules used to store large quantities of data, have been developed and found to possess many advantages over a single large disk drive. For example, the individual modules of a disk array typically take up very little space and typically use less power and cost less than a single large disk drive, yet, when grouped together in an array, provide the same data storage capacity as single large disk drive. In addition, the small disks of an array retrieve data more quickly than does a single large disk drive because, with a small disk drive, there is less distance for the actuator to travel and less data per individual disk to search through. The greatest advantage to small disk drives, however, is the boost they give to I/O performance when configured as a disk array subsystem.
In a disk array configuration, multiple drives process concurrent data retrieval/storage requests. Supported by a software "device driver" and individual controllers, the disks operate simultaneously. While one disk drive is retrieving/storing data, another can be sending data to the CPU. With several disks performing overlapped seeks, data can be retrieved and delivered more rapidly to the CPU. The CPU spends less time idle, so overall system performance improves substantially.
Examples of known disk array subsystems are the Data General Corp. High Availability Disk Array (H.A.D.A.) subsystem and the Data General Corp. Combined Storage Subsystem 2 (CSS2) subsystem. Both of these disk array subsystems use 5.25 inch disk drives.
Accordingly, it is an object of the present invention to provide a new and novel disk array subsystem.
It is another object of the present invention to provide a new and novel disk drive module for use in a disk array subsystem.
It is still another object of the present invention to provide a disk array subsystem having a plurality of disk drive modules and wherein the individual disk drive modules can be easily replaced when necessary.
It is still yet another object of the present invention to provide a disk array subsystem as described above whose size and shape conform to industry standards for purposes of modularity and, yet, which has the capacity to include a maximal number of disk drive modules.
It Is a further object of the present invention to provide a disk array subsystem as described above which uses disk drive modules having 3.5 inch disk drives.
It is still a further object of the present invention to provide a disk array subsystem as described above which includes a chassis and a new and novel arrangement for slidably and removably mounting the disk drive modules in the chassis.
It is still yet a further object of the present invention to provide a disk array subsystem as described above which includes a new and novel arrangement for securing the disk drive modules in place within the chassis of the subsystem.
It is another object of the present invention to provide a disk array subsystem as described above which includes a new and novel arrangement for cooling the components contained in the disk array subsystem.